1. Field of the Invention
This invention relates to an operator's compartment that is supported for independent up and down movement on the side wall of a self-propelled mine vehicle, and more particularly to an operator's compartment arranged to move upwardly and downwardly independently of the up and down movement of the vehicle as the mine vehicle moves over the uneven surface of the mine floor.
2. Description of the Prior Art
Self-propelled haulage vehicles, such as shuttle cars, are used in mines for transporting dislodged material from a mining or loading machine out of the mine. The shuttle car includes a longitudinally extending compartment in which the mined material is loaded, and after loading the shuttle car moves from an area adjacent the mine face to a fixed haulage system where the coal is discharged from the shuttle car onto a conveyor belt.
The shuttle car is controlled from an operator's compartment that is rigidly secured to the side wall of the vehicle. Suitable controls are provided on the operator's compartment by which the operator controls the movement of the vehicle between the mine face and the discharge point and also operates the conveyor of the haulage compartment.
The machine operator in the operator's compartment is exposed to the mine roof and is, therefore, subject to serious injury from falling debris. It is known to utilize overhead canopies for protecting operators of various equipment in a mine from the hazard of roof falls. For a shuttle car, however, the limited overhead clearance above the operator's compartment does not permit installation of a canopy particuarly when the car operates in mine seam heights of less than 40 inches. With the operator's compartment fixed on the vehicle and raised above the mine floor to provide the necessary ground clearance between the bottom of the compartment and the mine floor, there is insufficient clearance above the top of the shuttle car for the installation of an overhead protective canopy. Also, where there is little clearance between the top of the canopy and the mine roof, the canopy will strike the mine roof as the shuttle car bounces when it moves over the uneven undulating mine floor.
U.S. Pat. No. 4,078,629 discloses a mine vehicle having an operator's compartment slidably attached thereto. The connecting method disclosed in U.S. Pat. No. 4,078,629 utilizes two guide rails located at either end of the operator's compartment mating with two guide tracks on the vehicle. If the compartment is slightly cocked then the guide rail/tracks of the operator's compartment tend to bind and jam. The cocking also causes galling to occur along the guide track surfaces.
Usually the binding or jamming problem occurs when the compartment is falling after hitting a bump. When the compartment falls after having encountered a bump the only downward force is the weight of the compartment. If two slide mechanisms or guide and rail combinations are utilized and if the cab is slightly cocked (due to manufacturing tolerances) one rail will contact its guide before the other. This side will have to support all of the weight of the platform and, because of the leverage generated between the central point where the weight is acting, the rail/guide combination forces generated are enough to cause the one contacting rail to bind in the guide. In other words, the friction force between the rail and the guide resulting from the reactant force (weight to distance from center to guide) between the rail and the guide is greater than the weight of the operator's compartment so that it cannot drop.
It has been found that by utilizing a single guide/rail arrangement at the center of the cab that the moment arm is reduced so that the weight on each side of the rail is approximately equal and there is very little reactant force developed between the rail and the guide. Since the reactant force is low the friction forces which prevent falling are also low and the operator's compartment weight is enough to allow it to drop as desired.